We know Olivia never had feelings for Lucas and only really tolerated him up until mc left. They may have tried dating, but most likely didn't go anywhere, and if what everyone theorizes is true, never even got to the point of even being physical. The only thing I'm not sure about is that Lucas does have a picture of Olivia, signifying that he does have feelings for her even during present time. Until we get more information, we won't really know until future updates.
Don't forget,
Ellie calls the MC "Daddy" a few times and says, she knows him from a meeting before. It's more than obvious, that she KNOWS who he is and that he is her biological father. This second chapter made it much more clearer. The MC just doesn't use his brain to put 1 and 1 together. He just thinks she wants him as a dad, because of the lies of Olivia and Lucas. Then Mia, Ellie and Nova indicate that Olivia got taken care only by "Mr. Kim", her dildo, and Nova even tells the MC that Olivia was never touched by another man. Then there is Olivias dislike for Lucas, she accepted him only as a friend of the MC and tolerated his presence for the sake of the MC, I don't think she would jump at Lucas right after the MC left, if she never had any feelings. I mean, if these additional hints aren't enough, than I don't know.
Oh and for all people who think, it's unreasonable to wait for the love to return and start dating again: there are plenty of people out there, who are divorced and either dated again after a long time or never again. And then there are some people who never got into dating. I have such examples in my family, one of my uncles dated my aunt, his 2. wife, after over 15y. He was married for over 10y and has 4 kids with his 1. wife. Inbetween there was no one, my own mother dated, after the divorce of my father, (married for 11y, also 4 kids) one guy for a week after over 12y and after that it took her again over 10y to date the next guy. One of my aunts never dated anyone her whole life up to now, she is now over 60y old. One of my female cousins never dated again after the divorce after 8y of marriage and 3 kids. If someone doesn't want to wait, they go out dating again, but keep in mind, Olivia just played the expierenced slut in front of the MC in the first half of the prologue (until Lily's death), she never was a slut. She wanted to wait even if she could have assumed that the MC would never return and found a way to be satisfied to a degree in form of
Mr. Kim. At least the MC was reasonable enough at the first meeting with Olivia, not to expect that she really waited for him. But you can see, it hurt her, when he calles them "good friends" and as soon as he starts to talk about Lucas and her, she is hurt again. Both scenes come shortly after eachother in Ch1. It made the whole "Lucas and Olivia are Ellies parents" story suspicious AF, Ch2 cleared it with the points I mentioned above.
I swear, some people want Lucas and Olivia to be together just for the sake of drama and maybe even cuck content, despite all the facts we have.
This very end of the update surprised me after all Lucas has always loved Olivia and he's trying to replace her but I can already see that this won't happen anytime soon since his great friend returned maybe they won't even be that anymore because jealousy destroys any friendship Man I'm already looking forward to the next update this game is amazing full of twists. 
